Carbonaceous materials have been utilized from long ago as bulk materials such as diamond and graphite. In recent years, however, carbonaceous materials are coming to attract attention also as a coating material and a functional thin-film material. Of these materials, thin films of amorphous carbon represented by diamond-like carbon (DLC) have a low coefficient of friction and are excellent in smoothness and wearing resistance and, hence, are used in applications such as protective films for aluminum-processing molds, tools, etc., protective films for optical elements, and coating of the sliding surfaces of magnetic heads. For forming such amorphous-carbon thin films, vapor-phase growth methods such as the high-frequency plasma method and the ionization vapor deposition method are mainly used. However, all of these techniques necessitate a large vacuum apparatus and, hence, are high in film formation cost. In addition, those techniques are unsuitable for the formation of a film having a large area.
Among the carbonaceous materials which are attracting attention in recent years are fullerenes. Fullerene is a general term for carbon molecules having a spherical closed-shell structure. Fullerenes have unique properties attributable to the molecular structure, such as ultraviolet-absorbing properties, photoconductivity, and photosensitizing properties, and are hence expected to be used in a wide range of applications including electronic materials, e.g., organic semiconductors, functional optical materials, and coating materials as a substitute for conventional amorphous-carbon thin films. Investigations on the formation of a thin fullerene film on a substrate are being made enthusiastically in recent years.
It is known that the thermal conductivity of fullerenes is about one-hundredth the thermal conductivity of graphite (Hisanori Shinohara and Yahachi Saito, Furāren No Kagaku To Butsuri). Fullerene films are expected to be utilized as a heat-protective film more suitable than ordinary carbon films.
Furthermore, fullerenes have an exceedingly low electrical conductivity and are hence expected to be utilized as an insulating film or as a high-resistance black matrix for color filters.
Fullerenes further have excellent properties when used as organic n-type semiconductor molecules. Fullerenes are hence expected to be utilized as an organic-semiconductor thin film.
It is extremely difficult to form a thin fullerene film by a vapor-phase growth method. Because of this, investigations on the formation of a thin fullerene film by a wet process, e.g., the solvent casting method, have been made (see, for example, non-patent document 1). However, fullerenes have low solubility in solvents and show a reduced tendency to be oriented because of the highly symmetrical spherical molecular structure thereof. It has therefore been difficult to obtain by a wet process, e.g., the solvent casting method, a film which has a sufficient film thickness and in which the fullerene molecules have been regularly oriented.
On the other hand, in order to improve the film-forming properties and solvent solubility of fullerenes, various fullerene derivatives are being investigated and various derivatives have been proposed (see, for example, patent document 1). Methods of forming a film from a fullerene derivative also are being investigated. For example, non-patent document 2 discloses a technique in which a chemically modified fullerene derivative is used to form an LB film or self-assembled monolayer (SAM) on an electroconductive substrate. Furthermore, patent document 2 discloses a structure including a substrate and, formed thereon, a layer of a fullerene derivative having a structure constituted of a fullerene and a liquid-crystalline functional group bonded thereto.    Patent Document 1: JP-A-2006-199674    Patent Document 2: JP-A-2003-238490    Non-Patent Document 1: Pavel Janda et al., Advanced Materials, Wiley VCH Verlag (Germany), December 1998, Vol. 10, No. 17, pp. 1434-1438    Non-Patent Document 2: Hiroshi Imahori et al., Journal of Physical Chemistry B, American Chemical Society, U.S.A., Aug. 10, 1999, Vol. 103, No. 34, pp. 7233-7237